Size designations can trip rental customers

Car rental companies define "big" and "small" in ways that can make a big difference in cost and comfort.

Consider the Toyota Corolla. The Environmental Protection Agency and the National Highway Traffic Safety Administration call the Corolla a compact car.

For the EPA, that means a car including 100 to 110 cubic feet of passenger and cargo space. For NHTSA, which categorizes vehicle sizes for purposes of crash testing, it means a car with a curb weight of 2,500 to 2,599 pounds.

The curb weight is the weight of the car as shipped from the plant with all of its fluids and original equipment. Curb weight does not include a driver, passengers and their cargo.

The automatic 2004 Toyota Corolla LE has a curb weight of 2,590 pounds. It also fits within the EPA's definition of "compact" with a combined 103.9 cubic feet of space for passengers and their stuff.

However, Hertz Car Rental rents the Corolla as a "midsize" car at many of its 1,900 locations in the U.S., according to a spokesman at the company's headquarters in Park Ridge, N.J.

Hertz is not alone. Numerous car-rental companies use their own vehicle size categories, often classifying small cars as midsize or full-size, depending on the vehicle's popularity.

"There is no federal rule that says car-rental companies must adopt our vehicle-size classifications," said Timothy Hurd, a spokesman for NHTSA. "In practice, they can classify vehicle sizes as they see fit in much the same way that various fast food companies have different meanings for `small' and `large' coffee cups," Hurd said.

Many travel experts recommend choosing the type vehicle you want to rent before showing up at the rental counter.

After determining the size and type of vehicle you will need for your trip, ask for a specific model, such as a Corolla or Chevrolet Malibu. If it isn't available, travel experts advise asking for "one like it."

The idea is to avoid renting more car than you want or getting less car than you need.